Influence of ibopamine on heart rate and arrhythmic pattern in patients with congestive heart failure. A double-blind multicentre study.

Ibopamine is a dopaminergic and adrenergic receptor agonist, which is active in the treatment of congestive heart failure. Since the long-term prognosis for patients with congestive heart failure remains very poor and the incidence of arrhythmic death is high, every new drug to be employed against this disease should be thoroughly tested in order to rule out any possible arrhythmogenic action. This multicentre study was designed to evaluate the effect of ibopamine versus placebo in double-blind conditions on heart rate, rhythm and electrical safety. Ibopamine was employed at a dose of 100 mg t.i.d. in 97 patients (aged 31-83 years) belonging to NYHA class II and III with congestive heart failure of different aetiology, but without any complex ventricular arrhythmias in basal conditions (couplets with R'-R" less than or equal to 400 msec, ventricular tachycardia, R on T phenomena). Using a random cross-over design the patients were submitted to 48 hr. Holter recordings in basal conditions and following 7 days of ibopamine and placebo treatment. No influence on heart rhythm was noted. No significant variations in maximum heart rate (ibopamine 117.7 +/- 20.9; placebo 118.1 +/- 20.7), medium heart rate (ibopamine 71.8 +/- 10.2; placebo 72.6 +/- 10.1) or minimum heart rate (ibopamine 55.3 +/- 11.7; placebo 54.6 +/- 10.6) were observed. The mean number/hr. of ectopic supraventricular beats was 26.1 +/- 61.9 after ibopamine and 21.7 +/- 35.8 after placebo (p = ns). The complexity of ectopic supraventricular beats did not change. The mean number/hr. of ectopic ventricular beats was 31.1 +/- 52.5 after ibopamine and 30.4 +/- 57.8 after placebo (p = ns). Neither the distribution of the patients among Lown classification nor the Final Score of the Italian Lown Classification (26.1 +/- 18.0 and 26.6 +/- 17.9 in the 1st and 2nd day of monitoring after ibopamine and 25.7 +/- 18.6 and 25.7 +/- 18.8 after placebo; p = ns) showed any difference between active treatment and placebo. Similar results were achieved when the patients were sub-divided into subgroups according to sequences of treatment (basal----ibopamine----placebo and basal----placebo----ibopamine), NYHA class II or III, aetiology of congestive heart failure (dilatative cardiomyopathy, ischemic cardiomyopathy and other aetiologies), associated treatment with digitalis or diuretics and the number and complexity of base ectopic ventricular beats. None of the patients experienced sustained ventricular tachycardia.(ABSTRACT TRUNCATED AT 400 WORDS)